W126

First, I was removing my fuel injectors to do a compression test, I looked in each of the pre-chambers for oil and carbon (as instructed). I found what appears to be in inconsistency. when looking into my number 3 pre-chamber I see a normal appearing tip of the glow plug and another "thing"--it is bulbous in the middle and then thins out as it goes toward the ends of the chamber (on the "normal" five chambers. But in number 3, it appears that in just this chamber the part does NOT to extend all of the way through the chamber on both sides (only one side). Is this normal? what is this part? Should I be concerned? (i have a picture but i can't figure out how to load it into this text box)

Fuel Squirts out, in a steady stream, of Electro-Hydraulic Actuator when starting and running. Then, the fuel that is squirted out, flows through a manufactured hole in the Upper Intake Manifold. Ultimately, the fuel runs down into Lower Collector.

Never did this before winter.

What's the deal?

About two months after replacing the vacuum pump, a sharp "ticking" sound started that seemed to come from the front of the engine, and that varied directly with the engine speed. Checking the power steering pump reservoir revealed it was about half full. I added fluid but the ticking was still there.

The next thing I did was to adjust the valves. While turning the engine by hand for this procedure, I noticed a sharp-but-hollow sounding "pop" coming up from deep inside the engine at the timing chain. The sound occurred at what seemed to be every complete revolution of the engine. It may have been every half-revolution, but in any case, the "popping" was occurring at consistent points in the rotation of the engine. I know the vacuum pump opens up into the crankcase...